<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <style>
    ul li {
      list-style-type: none;
      text-align: center;
    }
    * {
      margin: 0;
      padding: 0;
    }
    ul {
      overflow: hidden;
      transition: all 0.3s;
    }
    body,
    html {
      height: 100%;
      overflow: hidden;
    }
    .box {
      height:400px;
      background-color: #fff;
      margin: 220px auto;
      overflow: hidden;
    }
    ul li {
      color: black;
      font-size: 14px;
      height: 30px;
      line-height: 30px;
      transition: all 0.3s;
      opacity: 0.5;
    }
    li.light {
      font-size: 20px;
      opacity: 1;
    }
  </style>
  <body>
    <div class="box">
      <ul></ul>
    </div>
    <script src="./index.js"></script>
  </body>
</html>
